Arelith

ESF:Enchantment does not seem to allow a second dominated creature when using dominate monster. haven't tried dominate person yet to confirm it's only the one spell

This is a known bug from back when the change was implemented.

For some reason you need three dominates to make it work.
> Dominate Target
> Dominate second Target, first Target gets released
> Re-Dominate first Target again, now both are properly dominated.

The team is very aware of this issue and it'll hopefully be fixed eventually.

Another oddity here as well: Once you dominate them .. you cant release them via the radial menu -- just FYI on that.